The purpose of this research will be to compare the relative efficacy of radioreceptor and chemical assay methods measurements of blood levels of anti-psychotic drugs for predicting therapeutic response and side-effects of these drugs in schizophrenic patients. Patients will be treated with fixed clinical doses of haloperidol or thioridazine and blood samples will be drawn for the analysis of neuroleptic levels in plasma and red-cells. Radioreceptor assays will assess blood levels by competition with dopaminergic, muscarinic cholinergic, and alpha-adrenergic binding ligands. Chemical assays will use GLC and spectrofluorometric methods. Quantitative measures of diagnosis, clinical status, and side-effects will be made throughout the course of treatment. This research will help to better define the type of relationship between blood levels and clinical response to anti-psychotic drugs and help answer the question of whether radioreceptor assays of blood levels of neuroleptics may be equally or more useful for these clinical purposes than individual chemical assay procedures for each drug.